WO2022225145A1 - 포인트 클라우드 데이터 송신 장치, 포인트 클라우드 데이터 송신 방법, 포인트 클라우드 데이터 수신 장치 및 포인트 클라우드 데이터 수신 방법 - Google Patents

포인트 클라우드 데이터 송신 장치, 포인트 클라우드 데이터 송신 방법, 포인트 클라우드 데이터 수신 장치 및 포인트 클라우드 데이터 수신 방법 Download PDF

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WO2022225145A1
WO2022225145A1 PCT/KR2022/001353 KR2022001353W WO2022225145A1 WO 2022225145 A1 WO2022225145 A1 WO 2022225145A1 KR 2022001353 W KR2022001353 W KR 2022001353W WO 2022225145 A1 WO2022225145 A1 WO 2022225145A1
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Prior art keywords
point cloud
geometry
cloud data
data
point
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PCT/KR2022/001353
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English (en)
French (fr)
Korean (ko)
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허혜정
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엘지전자 주식회사
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Priority to CN202280029041.6A priority Critical patent/CN117178555A/zh
Priority to JP2023564540A priority patent/JP2024515203A/ja
Priority to KR1020237039172A priority patent/KR20230174237A/ko
Priority to EP22791848.9A priority patent/EP4329310A1/en
Publication of WO2022225145A1 publication Critical patent/WO2022225145A1/ko

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/50—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding
    • H04N19/597—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding specially adapted for multi-view video sequence encoding
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
    • H04N19/129—Scanning of coding units, e.g. zig-zag scan of transform coefficients or flexible macroblock ordering [FMO]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/134—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or criterion affecting or controlling the adaptive coding
    • H04N19/136—Incoming video signal characteristics or properties
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/134—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or criterion affecting or controlling the adaptive coding
    • H04N19/167—Position within a video image, e.g. region of interest [ROI]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
    • H04N19/182—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being a pixel
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/70—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals characterised by syntax aspects related to video coding, e.g. related to compression standards
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/90—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using coding techniques not provided for in groups H04N19/10-H04N19/85, e.g. fractals
    • H04N19/96—Tree coding, e.g. quad-tree coding

Definitions

  • Embodiments relate to a method and apparatus for processing point cloud content.
  • the point cloud content is content expressed as a point cloud, which is a set of points (points) belonging to a coordinate system representing a three-dimensional space.
  • Point cloud content can express three-dimensional media, and provides various services such as VR (Virtual Reality), AR (Augmented Reality), MR (Mixed Reality), and autonomous driving service. used to provide
  • VR Virtual Reality
  • AR Augmented Reality
  • MR Magnetic Reality
  • autonomous driving service used to provide
  • tens of thousands to hundreds of thousands of point data are required. Therefore, a method for efficiently processing a large amount of point data is required.
  • Embodiments provide an apparatus and method for efficiently processing point cloud data.
  • Embodiments provide a point cloud data processing method and apparatus for solving latency and encoding/decoding complexity.
  • a method of transmitting point cloud data may include encoding point cloud data; and transmitting a bitstream including the point cloud data; may include.
  • a method for receiving point cloud data may include: receiving a bitstream including point cloud data; and decoding the point cloud data; may include.
  • the apparatus and method according to the embodiments may process point cloud data with high efficiency.
  • the apparatus and method according to the embodiments may provide a high quality point cloud service.
  • the apparatus and method according to the embodiments may provide point cloud content for providing universal services such as a VR service and an autonomous driving service.
  • FIG. 1 shows an example of a point cloud content providing system according to embodiments.
  • FIG. 2 is a block diagram illustrating an operation of providing point cloud content according to embodiments.
  • FIG 3 shows an example of a point cloud video capture process according to embodiments.
  • FIG. 4 shows an example of a point cloud encoder according to embodiments.
  • FIG. 5 shows an example of a voxel according to embodiments.
  • FIG. 6 shows an example of an octree and an occupancy code according to embodiments.
  • FIG. 7 shows an example of a neighbor node pattern according to embodiments.
  • FIG. 10 shows an example of a point cloud decoder according to embodiments.
  • FIG. 11 shows an example of a point cloud decoder according to embodiments.
  • FIG. 13 is an example of a receiving apparatus according to embodiments.
  • FIG. 14 shows an example of a structure capable of interworking with a method/device for transmitting and receiving point cloud data according to embodiments.
  • 15 illustrates additional attribute data of point cloud data according to embodiments.
  • FIG 16 shows an example of an origin position with respect to point cloud data according to embodiments.
  • FIG 17 shows an example of an origin position according to embodiments.
  • 19 shows an example of laser angle-based alignment according to embodiments.
  • 20 shows an example of generating a laser group and a prediction tree according to embodiments.
  • 21 shows an apparatus for transmitting point cloud data according to embodiments.
  • FIG. 22 shows an apparatus for receiving point cloud data according to embodiments.
  • FIG. 23 shows a bitstream including point cloud data and parameter information according to embodiments.
  • 25 shows a set of geometric parameters according to embodiments.
  • 26 shows a tile parameter set according to embodiments.
  • FIG. 27 illustrates a geometry slice header according to embodiments.
  • 29 shows a method of receiving point cloud data according to embodiments.
  • FIG. 1 shows an example of a point cloud content providing system according to embodiments.
  • the point cloud content providing system shown in FIG. 1 may include a transmission device 10000 and a reception device 10004 .
  • the transmitting device 10000 and the receiving device 10004 are capable of wired/wireless communication in order to transmit/receive point cloud data.
  • the transmission device 10000 may secure, process, and transmit a point cloud video (or point cloud content).
  • the transmitting device 10000 is a fixed station, a base transceiver system (BTS), a network, an Ariticial Intelligence (AI) device and/or system, a robot, an AR/VR/XR device and/or a server and the like.
  • BTS base transceiver system
  • AI Ariticial Intelligence
  • robot an AR/VR/XR device and/or a server and the like.
  • the transmission device 10000 uses a radio access technology (eg, 5G NR (New RAT), LTE (Long Term Evolution)), a device that performs communication with a base station and/or other wireless devices, It may include robots, vehicles, AR/VR/XR devices, mobile devices, home appliances, Internet of Things (IoT) devices, AI devices/servers, and the like.
  • a radio access technology eg, 5G NR (New RAT), LTE (Long Term Evolution)
  • a device that performs communication with a base station and/or other wireless devices It may include robots, vehicles, AR/VR/XR devices, mobile devices, home appliances, Internet of Things (IoT) devices, AI devices/servers, and the like.
  • IoT Internet of Things
  • Transmission device 10000 is a point cloud video acquisition unit (Point Cloud Video Acquisition, 10001), a point cloud video encoder (Point Cloud Video Encoder, 10002) and / or a transmitter (Transmitter (or Communication module), 10003) ) contains
  • the point cloud video acquisition unit 10001 acquires the point cloud video through processing such as capturing, synthesizing, or generating.
  • the point cloud video is point cloud content expressed as a point cloud that is a set of points located in a three-dimensional space, and may be referred to as point cloud video data or the like.
  • a point cloud video according to embodiments may include one or more frames. One frame represents a still image/picture. Accordingly, the point cloud video may include a point cloud image/frame/picture, and may be referred to as any one of a point cloud image, a frame, and a picture.
  • the point cloud video encoder 10002 encodes the obtained point cloud video data.
  • the point cloud video encoder 10002 may encode point cloud video data based on point cloud compression coding.
  • Point cloud compression coding may include Geometry-based Point Cloud Compression (G-PCC) coding and/or Video based Point Cloud Compression (V-PCC) coding or next-generation coding.
  • G-PCC Geometry-based Point Cloud Compression
  • V-PCC Video based Point Cloud Compression
  • point cloud compression coding according to the embodiments is not limited to the above-described embodiments.
  • the point cloud video encoder 10002 may output a bitstream including encoded point cloud video data.
  • the bitstream may include not only the encoded point cloud video data, but also signaling information related to encoding of the point cloud video data.
  • the transmitter 10003 transmits a bitstream including encoded point cloud video data.
  • a bitstream according to embodiments is encapsulated into a file or segment (eg, a streaming segment) and transmitted through various networks such as a broadcasting network and/or a broadband network.
  • the transmission device 10000 may include an encapsulation unit (or an encapsulation module) that performs an encapsulation operation.
  • the encapsulation unit may be included in the transmitter 10003 .
  • the file or segment may be transmitted to the receiving device 10004 through a network or stored in a digital storage medium (eg, USB, SD, CD, DVD, Blu-ray, HDD, SSD, etc.).
  • the transmitter 10003 may communicate with the receiving device 10004 (or a receiver 10005) through wired/wireless communication through networks such as 4G, 5G, and 6G. Also, the transmitter 10003 may perform a necessary data processing operation according to a network system (eg, a communication network system such as 4G, 5G, or 6G). Also, the transmission device 10000 may transmit encapsulated data according to an on demand method.
  • a network system eg, a communication network system such as 4G, 5G, or 6G.
  • the transmission device 10000 may transmit encapsulated data according to an on demand method.
  • the receiving device 10004 includes a receiver (Receiver, 10005), a point cloud video decoder (Point Cloud Decoder, 10006), and/or a renderer (Renderer, 10007).
  • the receiving device 10004 uses a radio access technology (eg, 5G NR (New RAT), LTE (Long Term Evolution)) to communicate with a base station and/or other wireless devices, a device or a robot.
  • a radio access technology eg, 5G NR (New RAT), LTE (Long Term Evolution)
  • the receiver 10005 receives a bitstream including point cloud video data or a file/segment in which the bitstream is encapsulated from a network or a storage medium.
  • the receiver 10005 may perform a necessary data processing operation according to a network system (eg, a communication network system such as 4G, 5G, or 6G).
  • the receiver 10005 may output a bitstream by decapsulating the received file/segment.
  • the receiver 10005 may include a decapsulation unit (or a decapsulation module) for performing a decapsulation operation.
  • the decapsulation unit may be implemented as an element (or component) separate from the receiver 10005 .
  • the point cloud video decoder 10006 decodes a bitstream including point cloud video data.
  • the point cloud video decoder 10006 may decode the point cloud video data according to an encoded manner (eg, a reverse process of the operation of the point cloud video encoder 10002 ). Accordingly, the point cloud video decoder 10006 may decode the point cloud video data by performing point cloud decompression coding, which is a reverse process of the point cloud compression.
  • Point cloud decompression coding includes G-PCC coding.
  • the renderer 10007 renders the decoded point cloud video data.
  • the renderer 10007 may output point cloud content by rendering audio data as well as point cloud video data.
  • the renderer 10007 may include a display for displaying the point cloud content.
  • the display may not be included in the renderer 10007 and may be implemented as a separate device or component.
  • the feedback information is information for reflecting an interactivity with a user who consumes the point cloud content, and includes user information (eg, head orientation information, viewport information, etc.).
  • user information eg, head orientation information, viewport information, etc.
  • the feedback information is provided by the content transmitting side (eg, the transmission device 10000) and/or the service provider can be passed on to According to embodiments, the feedback information may be used by the receiving device 10004 as well as the transmitting device 10000 or may not be provided.
  • the head orientation information is information about the user's head position, direction, angle, movement, and the like.
  • the reception apparatus 10004 may calculate viewport information based on head orientation information.
  • the viewport information is information about the area of the point cloud video that the user is looking at.
  • a viewpoint is a point at which a user is watching a point cloud video, and may mean a central point of the viewport area. That is, the viewport is an area centered on a viewpoint, and the size and shape of the area may be determined by a Field Of View (FOV).
  • FOV Field Of View
  • the reception device 10004 may extract viewport information based on a vertical or horizontal FOV supported by the device in addition to the head orientation information.
  • the receiving device 10004 checks the user's point cloud consumption method, the point cloud video area the user gazes at, the gaze time, and the like by performing a gaze analysis or the like.
  • the receiving device 10004 may transmit feedback information including the result of the gaze analysis to the transmitting device 10000 .
  • Feedback information may be obtained during rendering and/or display.
  • the feedback information according to embodiments may be secured by one or more sensors included in the receiving device 10004 .
  • the feedback information may be secured by the renderer 10007 or a separate external element (or device, component, etc.).
  • a dotted line in FIG. 1 shows a process of transmitting feedback information secured by the renderer 10007 .
  • the point cloud content providing system may process (encode/decode) the point cloud data based on the feedback information. Accordingly, the point cloud video data decoder 10006 may perform a decoding operation based on the feedback information. Also, the receiving device 10004 may transmit feedback information to the transmitting device 10000 . The transmitting device 10000 (or the point cloud video data encoder 10002 ) may perform an encoding operation based on the feedback information. Therefore, the point cloud content providing system does not process (encode/decode) all point cloud data, but efficiently processes necessary data (for example, point cloud data corresponding to the user's head position) based on the feedback information, and the user can provide point cloud content to
  • the transmitting apparatus 10000 may be referred to as an encoder, a transmitting device, a transmitter, etc.
  • the receiving apparatus 10004 may be referred to as a decoder, a receiving device, a receiver, or the like.
  • Point cloud data (processed in a series of acquisition/encoding/transmission/decoding/rendering) processed in the point cloud content providing system of FIG. 1 according to embodiments may be referred to as point cloud content data or point cloud video data.
  • the point cloud content data may be used as a concept including metadata or signaling information related to the point cloud data.
  • the elements of the point cloud content providing system shown in FIG. 1 may be implemented by hardware, software, a processor and/or a combination thereof.
  • FIG. 2 is a block diagram illustrating an operation of providing point cloud content according to embodiments.
  • the block diagram of FIG. 2 shows the operation of the point cloud content providing system described in FIG. 1 .
  • the point cloud content providing system may process point cloud data based on point cloud compression coding (eg, G-PCC).
  • point cloud compression coding eg, G-PCC
  • the point cloud content providing system may acquire a point cloud video (20000).
  • a point cloud video is expressed as a point cloud belonging to a coordinate system representing a three-dimensional space.
  • a point cloud video according to embodiments may include a Ply (Polygon File format or the Stanford Triangle format) file.
  • the acquired point cloud video may include one or more Ply files.
  • the Ply file contains point cloud data such as the point's geometry and/or attributes. Geometry includes positions of points.
  • the position of each point may be expressed by parameters (eg, values of each of the X-axis, Y-axis, and Z-axis) representing a three-dimensional coordinate system (eg, a coordinate system including XYZ axes).
  • the attribute includes attributes of points (eg, texture information of each point, color (YCbCr or RGB), reflectance (r), transparency, etc.).
  • a point has one or more attributes (or properties).
  • one point may have one attribute of color, or two attributes of color and reflectance.
  • the geometry may be referred to as positions, geometry information, geometry data, and the like, and the attribute may be referred to as attributes, attribute information, attribute data, and the like.
  • the point cloud content providing system receives points from information (eg, depth information, color information, etc.) related to the point cloud video acquisition process. Cloud data can be obtained.
  • the point cloud content providing system may encode the point cloud data (20001).
  • the point cloud content providing system may encode point cloud data based on point cloud compression coding.
  • the point cloud data may include the geometry and attributes of the point.
  • the point cloud content providing system may output a geometry bitstream by performing geometry encoding for encoding the geometry.
  • the point cloud content providing system may output an attribute bitstream by performing attribute encoding for encoding the attribute.
  • the point cloud content providing system may perform attribute encoding based on geometry encoding.
  • the geometry bitstream and the attribute bitstream according to the embodiments may be multiplexed and output as one bitstream.
  • the bitstream according to embodiments may further include signaling information related to geometry encoding and attribute encoding.
  • the point cloud content providing system may transmit the encoded point cloud data (20002).
  • the encoded point cloud data may be expressed as a geometry bitstream and an attribute bitstream.
  • the encoded point cloud data may be transmitted in the form of a bitstream together with signaling information related to encoding of the point cloud data (eg, signaling information related to geometry encoding and attribute encoding).
  • the point cloud content providing system may encapsulate the bitstream for transmitting the encoded point cloud data and transmit it in the form of a file or segment.
  • the point cloud content providing system (eg, the receiving device 10004 or the receiver 10005) according to the embodiments may receive a bitstream including the encoded point cloud data. Also, the point cloud content providing system (eg, the receiving device 10004 or the receiver 10005) may demultiplex the bitstream.
  • the point cloud content providing system may decode the encoded point cloud data (for example, a geometry bitstream, an attribute bitstream) transmitted as a bitstream. have.
  • the point cloud content providing system (for example, the receiving device 10004 or the point cloud video decoder 10005) may decode the point cloud video data based on signaling information related to encoding of the point cloud video data included in the bitstream. have.
  • the point cloud content providing system (for example, the receiving device 10004 or the point cloud video decoder 10005) may decode the geometry bitstream to restore positions (geometry) of the points.
  • the point cloud content providing system may restore attributes of points by decoding an attribute bitstream based on the restored geometry.
  • the point cloud content providing system (for example, the receiving device 10004 or the point cloud video decoder 10005) may reconstruct the point cloud video based on positions and decoded attributes according to the reconstructed geometry.
  • the point cloud content providing system may render the decoded point cloud data (20004).
  • the point cloud content providing system eg, the receiving device 10004 or the renderer 10007) may render the geometry and attributes decoded through the decoding process according to various rendering methods according to the rendering method. Points of the point cloud content may be rendered as a vertex having a certain thickness, a cube having a specific minimum size centered at the vertex position, or a circle centered at the vertex position. All or part of the rendered point cloud content is provided to the user through a display (eg, VR/AR display, general display, etc.).
  • a display eg, VR/AR display, general display, etc.
  • the point cloud content providing system (eg, the receiving device 10004) according to the embodiments may secure feedback information (20005).
  • the point cloud content providing system may encode and/or decode the point cloud data based on the feedback information. Since the operation of the feedback information and point cloud content providing system according to the embodiments is the same as the feedback information and operation described with reference to FIG. 1 , a detailed description thereof will be omitted.
  • FIG 3 shows an example of a point cloud video capture process according to embodiments.
  • FIG. 3 shows an example of a point cloud video capture process of the point cloud content providing system described with reference to FIGS. 1 to 2 .
  • the point cloud content is an object located in various three-dimensional spaces (eg, a three-dimensional space representing a real environment, a three-dimensional space representing a virtual environment, etc.) and/or a point cloud video representing the environment (images and/or videos) are included.
  • the point cloud content providing system includes one or more cameras (eg, an infrared camera capable of securing depth information, color information corresponding to the depth information) in order to generate point cloud content.
  • Point cloud video can be captured using an RGB camera that can extract
  • the point cloud content providing system according to the embodiments may extract a shape of a geometry composed of points in a three-dimensional space from depth information, and extract an attribute of each point from color information to secure point cloud data.
  • An image and/or an image according to embodiments may be captured based on at least one of an inward-facing method and an outward-facing method.
  • the left side of FIG. 3 shows an inward-pacing scheme.
  • the inward-pacing method refers to a method in which one or more cameras (or camera sensors) located surrounding the central object capture the central object.
  • the inward-facing method provides a 360-degree image of a point cloud content that provides a 360-degree image of a core object to the user (for example, a 360-degree image of an object (e.g., a core object such as a character, player, object, actor, etc.) to the user.
  • VR/AR content for example, a 360-degree image of an object (e.g., a core object such as a character, player, object, actor, etc.)
  • the right side of FIG. 3 shows an outward-pacing scheme.
  • the outward-pacing method refers to a method in which one or more cameras (or camera sensors) positioned surrounding the central object capture the environment of the central object rather than the central object.
  • the outward-pacing method may be used to generate point cloud content (eg, content representing an external environment that may be provided to a user of an autonomous vehicle) for providing a surrounding environment that appears from the user's point of view.
  • point cloud content eg, content representing an external environment that may be provided to a user of an autonomous vehicle
  • the point cloud content may be generated based on a capture operation of one or more cameras.
  • the point cloud content providing system may perform calibration of one or more cameras in order to set a global coordinate system before a capture operation.
  • the point cloud content providing system may generate the point cloud content by synthesizing the image and/or image captured by the above-described capture method and an arbitrary image and/or image.
  • the point cloud content providing system may not perform the capture operation described with reference to FIG. 3 when generating point cloud content representing a virtual space.
  • the point cloud content providing system according to the embodiments may perform post-processing on the captured image and/or the image. That is, the point cloud content providing system removes an unwanted area (for example, a background), recognizes a space where captured images and/or images are connected, and fills in a spatial hole if there is one. can
  • the point cloud content providing system may generate one point cloud content by performing coordinate system transformation on points of the point cloud video obtained from each camera.
  • the point cloud content providing system may perform coordinate system transformation of points based on the position coordinates of each camera. Accordingly, the point cloud content providing system may generate content representing one wide range and may generate point cloud content having a high density of points.
  • FIG. 4 shows an example of a point cloud encoder according to embodiments.
  • the point cloud encoder controls point cloud data (eg, positions of points and/or attributes) and perform the encoding operation.
  • point cloud data e.g, positions of points and/or attributes
  • the point cloud content providing system may not be able to stream the corresponding content in real time. Accordingly, the point cloud content providing system may reconfigure the point cloud content based on a maximum target bitrate in order to provide it according to a network environment and the like.
  • the point cloud encoder may perform geometry encoding and attribute encoding. Geometry encoding is performed before attribute encoding.
  • a point cloud encoder may include a coordinate system transformation unit (Transformation Coordinates, 40000), a quantization unit (Quantize and Remove Points (Voxelize), 40001), an octree analysis unit (Analyze Octree, 40002), and a surface approximation analysis unit ( Analyze Surface Approximation (40003), Arithmetic Encode (40004), Reconstruct Geometry (40005), Color Transformer (Transform Colors, 40006), Attribute Transformer (Transfer Attributes, 40007), RAHT Transform It includes a unit 40008, an LOD generator (Generated LOD, 40009), a lifting transform unit (Lifting) 40010, a coefficient quantization unit (Quantize Coefficients, 40011) and/or an arithmetic encoder (Arithmetic Encode, 40012).
  • a coordinate system transformation unit Transformation Coordinates, 40000
  • a quantization unit Quantization and Remove Points (Voxelize)
  • the coordinate system transformation unit 40000, the quantization unit 40001, the octree analysis unit 40002, the surface approximation analysis unit 40003, the arithmetic encoder 40004, and the geometry reconstruction unit 40005 perform geometry encoding. can do.
  • Geometry encoding according to embodiments may include octree geometry coding, direct coding, trisoup geometry encoding, and entropy encoding. Direct coding and trisup geometry encoding are applied selectively or in combination. Also, the geometry encoding is not limited to the above example.
  • the coordinate system conversion unit 40000 receives the positions and converts them into a coordinate system.
  • the positions may be converted into position information in a three-dimensional space (eg, a three-dimensional space expressed in an XYZ coordinate system, etc.).
  • Location information in 3D space may be referred to as geometry information.
  • the quantizer 40001 quantizes the geometry. For example, the quantizer 40001 may quantize the points based on the minimum position values of all points (eg, the minimum values on each axis with respect to the X-axis, Y-axis, and Z-axis).
  • the quantization unit 40001 performs a quantization operation to find the nearest integer value by multiplying the difference between the minimum position value and the position value of each point by a preset quatization scale value, and then rounding up or down. Accordingly, one or more points may have the same quantized position (or position value).
  • the quantizer 40001 according to embodiments performs voxelization based on quantized positions to reconstruct quantized points.
  • a minimum unit including 2D image/video information is a pixel, and points of point cloud content (or 3D point cloud video) according to embodiments may be included in one or more voxels.
  • the quantizer 40001 may match groups of points in a 3D space to voxels.
  • one voxel may include only one point.
  • one voxel may include one or more points.
  • a position of a center point of a corresponding voxel may be set based on positions of one or more points included in one voxel.
  • attributes of all positions included in one voxel may be combined and assigned to a corresponding voxel.
  • the octree analyzer 40002 performs octree geometry coding (or octree coding) to represent voxels in an octree structure.
  • the octree structure represents points matched to voxels based on the octal tree structure.
  • the surface approximation analyzer 40003 may analyze and approximate the octree.
  • Octree analysis and approximation is a process of analyzing to voxelize a region including a plurality of points in order to efficiently provide octree and voxelization.
  • the arithmetic encoder 40004 entropy encodes the octree and/or the approximated octree.
  • the encoding method includes an arithmetic encoding method.
  • the encoding results in a geometry bitstream.
  • Color transform unit 40006, attribute transform unit 40007, RAHT transform unit 40008, LOD generation unit 40009, lifting transform unit 40010, coefficient quantization unit 40011 and/or arithmetic encoder 40012 performs attribute encoding.
  • a point can have one or more attributes. Attribute encoding according to embodiments is equally applied to attributes of one point. However, when one attribute (eg, color) includes one or more elements, independent attribute encoding is applied to each element.
  • Attribute encoding may include color transform coding, attribute transform coding, region adaptive hierarchical transform (RAHT) coding, interpolaration-based hierarchical nearest-neighbor prediction-Prediction Transform coding, and interpolation-based hierarchical nearest -neighbor prediction with an update/lifting step (Lifting Transform)) coding.
  • RAHT region adaptive hierarchical transform
  • RAHT interpolaration-based hierarchical nearest-neighbor prediction-Prediction Transform
  • Lifting Transform interpolation-based hierarchical nearest -neighbor prediction with an update/lifting step
  • attribute encoding is not limited to the above-described example.
  • the color conversion unit 40006 performs color conversion coding for converting color values (or textures) included in attributes.
  • the color converter 40006 may convert the format of color information (eg, convert from RGB to YCbCr).
  • the operation of the color converter 40006 according to embodiments may be optionally applied according to color values included in the attributes.
  • the geometry reconstruction unit 40005 reconstructs (decompresses) an octree and/or an approximated octree.
  • the geometry reconstruction unit 40005 reconstructs an octree/voxel based on a result of analyzing the distribution of points.
  • the reconstructed octree/voxel may be referred to as a reconstructed geometry (or a reconstructed geometry).
  • the attribute transform unit 40007 performs an attribute transform that transforms attributes based on positions where geometry encoding has not been performed and/or a reconstructed geometry. As described above, since the attributes are dependent on the geometry, the attribute conversion unit 40007 may transform the attributes based on the reconstructed geometry information. For example, the attribute conversion unit 40007 may convert an attribute of a point at the position based on the position value of the point included in the voxel. As described above, when the position of the center point of a corresponding voxel is set based on the positions of one or more points included in one voxel, the attribute conversion unit 40007 converts attributes of the one or more points. When the trisoop geometry encoding has been performed, the attribute conversion unit 40007 may convert the attributes based on the trisoop geometry encoding.
  • the attribute conversion unit 40007 is an average value of attributes or attribute values (for example, color or reflectance of each point) of neighboring points within a specific position/radius from the position (or position value) of the central point of each voxel. can be calculated to perform attribute transformation.
  • the attribute conversion unit 40007 may apply a weight according to the distance from the center point to each point when calculating the average value.
  • each voxel has a position and a computed attribute (or attribute value).
  • the attribute transform unit 40007 may search for neighboring points existing within a specific position/radius from the position of the center point of each voxel based on the K-D tree or the Morton code.
  • K-D tree is a binary search tree, and supports a data structure that can manage points based on location so that Nearest Neighbor Search-NNS is possible quickly.
  • the Molton code is generated by representing a coordinate value (eg (x, y, z)) representing a three-dimensional position of all points as a bit value and mixing the bits. For example, if the coordinate value indicating the position of the point is (5, 9, 1), the bit value of the coordinate value is (0101, 1001, 0001).
  • the attribute transform unit 40007 may align the points based on the Molton code value and perform a shortest neighbor search (NNS) through a depth-first traversal process. After the attribute transform operation, when the nearest neighbor search (NNS) is required in another transform process for attribute coding, a K-D tree or a Molton code is used.
  • NSS shortest neighbor search
  • the converted attributes are input to the RAHT conversion unit 40008 and/or the LOD generation unit 40009.
  • the RAHT converter 40008 performs RAHT coding for predicting attribute information based on the reconstructed geometry information.
  • the RAHT transform unit 40008 may predict attribute information of a node at an upper level of the octree based on attribute information associated with a node at a lower level of the octree.
  • the LOD generator 40009 generates a level of detail (LOD) to perform predictive transform coding.
  • LOD level of detail
  • the LOD according to the embodiments represents the detail of the point cloud content, and as the LOD value is smaller, the detail of the point cloud content is decreased, and as the LOD value is larger, the detail of the point cloud content is higher. Points may be classified according to LOD.
  • the lifting transform unit 40010 performs lifting transform coding that transforms the attributes of the point cloud based on weights. As described above, lifting transform coding may be selectively applied.
  • the coefficient quantizer 40011 quantizes the attribute-coded attributes based on the coefficients.
  • the arithmetic encoder 40012 encodes the quantized attributes based on arithmetic coding.
  • the elements of the point cloud encoder of FIG. 4 are hardware including one or more processors or integrated circuits configured to communicate with one or more memories included in the point cloud providing device. , software, firmware, or a combination thereof.
  • the one or more processors may perform at least any one or more of the operations and/or functions of the elements of the point cloud encoder of FIG. 4 described above.
  • the one or more processors may also operate or execute a set of software programs and/or instructions for performing the operations and/or functions of the elements of the point cloud encoder of FIG. 4 .
  • One or more memories in accordance with embodiments may include high speed random access memory, non-volatile memory (eg, one or more magnetic disk storage devices, flash memory devices, or other non-volatile solid state memory). memory devices (such as solid-state memory devices).
  • FIG. 5 shows an example of a voxel according to embodiments.
  • voxel 5 is an octree structure that recursively subdivides a bounding box defined by two poles (0,0,0) and (2 d , 2 d , 2 d ).
  • An example of a voxel generated through One voxel includes at least one or more points.
  • a voxel may estimate spatial coordinates from a positional relationship with a voxel group.
  • voxels have attributes (such as color or reflectance) like pixels of a 2D image/image.
  • a detailed description of the voxel is the same as that described with reference to FIG. 4 , and thus will be omitted.
  • FIG. 6 shows an example of an octree and an occupancy code according to embodiments.
  • the point cloud content providing system (point cloud video encoder 10002) or point cloud encoder (eg, octree analysis unit 40002) efficiently manages the area and/or position of voxels To do this, octree geometry coding (or octree coding) based on an octree structure is performed.
  • FIG. 6 shows the octree structure.
  • the three-dimensional space of the point cloud content according to the embodiments is expressed by axes (eg, X-axis, Y-axis, and Z-axis) of the coordinate system.
  • the octree structure is created by recursive subdividing a cubic axis-aligned bounding box defined by two poles (0,0,0) and (2 d , 2 d , 2 d ). . 2d may be set to a value constituting the smallest bounding box surrounding all points of the point cloud content (or point cloud video).
  • d represents the depth of the octree.
  • the value of d is determined according to the following equation. In the following equation (x int n , y int n , z int n ) represents positions (or position values) of quantized points.
  • the entire 3D space may be divided into eight spaces according to the division.
  • Each divided space is represented by a cube with six faces.
  • each of the eight spaces is again divided based on the axes of the coordinate system (eg, X-axis, Y-axis, and Z-axis). Therefore, each space is further divided into 8 small spaces.
  • the divided small space is also expressed as a cube with six faces. This division method is applied until a leaf node of the octree becomes a voxel.
  • the lower part of Fig. 6 shows the occupancy code of the octree.
  • the occupancy code of the octree is generated to indicate whether each of the eight divided spaces generated by dividing one space includes at least one point.
  • one occupanci code is expressed by eight child nodes.
  • Each child node represents the occupancies of the divided space, and each child node has a value of 1 bit. Therefore, the occupanci code is expressed as an 8-bit code. That is, if at least one point is included in the space corresponding to the child node, the corresponding node has a value of 1. If the space corresponding to the child node does not contain a point (empty), the node has a value of 0. Since the occupancy code shown in FIG.
  • a point cloud encoder (eg, arithmetic encoder 40004 ) according to embodiments may entropy encode the occupanci code. In addition, to increase the compression efficiency, the point cloud encoder can intra/inter-code the occupanci code.
  • the receiving apparatus (eg, the receiving apparatus 10004 or the point cloud video decoder 10006) according to embodiments reconstructs an octree based on the occupanci code.
  • the point cloud encoder (eg, the point cloud encoder of FIG. 4 , or the octree analyzer 40002 ) according to embodiments may perform voxelization and octree coding to store positions of points.
  • the points in the 3D space are not always evenly distributed, there may be a specific area where there are not many points. Therefore, it is inefficient to perform voxelization on the entire 3D space. For example, if there are few points in a specific area, it is not necessary to perform voxelization up to the corresponding area.
  • the point cloud encoder does not perform voxelization on the above-described specific region (or a node other than a leaf node of an octree), but directly codes positions of points included in the specific region. ) can be done. Coordinates of direct coding points according to embodiments are called direct coding mode (DCM).
  • DCM direct coding mode
  • the point cloud encoder according to the embodiments may perform trisoup geometry encoding for reconstructing positions of points in a specific region (or node) based on a voxel based on a surface model.
  • Tri-Soop geometry encoding is a geometry encoding that expresses the representation of an object as a series of triangle meshes.
  • the point cloud decoder can generate a point cloud from the mesh surface.
  • Direct coding and trisup geometry encoding according to embodiments may be selectively performed. Also, direct coding and trisup geometry encoding according to embodiments may be performed in combination with octree geometry coding (or octree coding).
  • the option to use a direct mode for applying direct coding must be activated, and a node to which direct coding is to be applied is not a leaf node, but is less than a threshold within a specific node. points must exist. In addition, the number of whole points to be subjected to direct coding must not exceed a preset limit value. If the above condition is satisfied, the point cloud encoder (or the arithmetic encoder 40004 ) according to embodiments may entropy-code positions (or position values) of points.
  • the point cloud encoder (for example, the surface approximation analysis unit 40003) according to the embodiments determines a specific level of the octree (when the level is smaller than the depth d of the octree), and from that level, a node using the surface model It is possible to perform tri-soup geometry encoding that reconstructs the position of a point in a region based on voxels (tri-soup mode).
  • the point cloud encoder may designate a level to which the trisup geometry encoding is to be applied. For example, if the specified level is equal to the depth of the octree, the point cloud encoder will not operate in tri-soup mode.
  • the point cloud encoder may operate in the tri-soup mode only when the specified level is smaller than the depth value of the octree.
  • a three-dimensional cube region of nodes of a designated level according to embodiments is called a block.
  • One block may include one or more voxels.
  • a block or voxel may correspond to a brick.
  • the geometry is represented as a surface.
  • a surface according to embodiments may intersect each edge of the block at most once.
  • a vertex existing along an edge is detected when there is at least one occupied voxel adjacent to the edge among all blocks sharing the edge.
  • An ocupided voxel means a voxel including a point. The position of the vertex detected along the edge is the average position along the edge of all voxels of all voxels adjacent to the edge among all blocks sharing the edge.
  • the point cloud encoder When a vertex is detected, the point cloud encoder according to the embodiments entropy-codes the starting point (x, y, z) of the edge, the direction vectors ( ⁇ x, ⁇ y, ⁇ z) of the edge, and the vertex position values (relative position values within the edge).
  • the point cloud encoder eg, the geometry reconstruction unit 40005
  • the point cloud encoder performs triangle reconstruction, up-sampling, and voxelization. to create a reconstructed geometry (reconstructed geometry).
  • Vertices located at the edge of a block determine the surface that passes through the block.
  • the surface according to embodiments is a non-planar polygon.
  • the triangle reconstruction process reconstructs the surface represented by a triangle based on the starting point of the edge, the direction vector of the edge, and the position value of the vertex.
  • the triangle reconstruction process is as follows. 1 Calculate the centroid value of each vertex, 2 perform a square on the values obtained by subtracting the centroid value from each vertex value, and obtain the sum of all the values.
  • each vertex is projected on the x-axis with respect to the center of the block and projected on the (y, z) plane. If the value that comes out when projecting to the (y, z) plane is (ai, bi), the ⁇ value is obtained through atan2(bi, ai), and the vertices are aligned based on the ⁇ value.
  • the table below shows combinations of vertices for generating a triangle according to the number of vertices. Vertices are sorted in order from 1 to n.
  • the table below shows that for four vertices, two triangles can be formed according to a combination of vertices.
  • the first triangle may be composed of 1st, 2nd, and 3rd vertices among the aligned vertices
  • the second triangle may be composed of 3rd, 4th, and 1st vertices among the aligned vertices. .
  • the upsampling process is performed to voxelize the triangle by adding points along the edge of the triangle. Create additional points based on the upsampling factor and the width of the block. The additional points are called refined vertices.
  • the point cloud encoder may voxel the refined vertices. Also, the point cloud encoder may perform attribute encoding based on the voxelized position (or position value).
  • FIG. 7 shows an example of a neighbor node pattern according to embodiments.
  • the point cloud encoder may perform entropy coding based on context adaptive arithmetic coding.
  • the point cloud content providing system or point cloud encoder (for example, the point cloud video encoder 10002, the point cloud encoder or the arithmetic encoder 40004 of FIG. 4) directly transmits the occupanci code.
  • Entropy coding is possible.
  • the point cloud content providing system or point cloud encoder performs entropy encoding (intra-encoding) based on the occupancies of the current node and the occupancies of neighboring nodes, or entropy-encoding (inter-encoding) based on the occupancies of the previous frame. ) can be done.
  • a frame according to embodiments means a set of point cloud videos generated at the same time.
  • a point cloud encoder determines occupancy of neighboring nodes of each node of an octree and obtains a neighbor pattern value.
  • the neighbor node pattern is used to infer the occupancy pattern of the corresponding node.
  • the left side of FIG. 7 shows a cube corresponding to a node (a cube located in the center) and six cubes (neighboring nodes) that share at least one face with the cube.
  • the nodes shown in the figure are nodes of the same depth (depth).
  • the numbers shown in the figure represent the weights (1, 2, 4, 8, 16, 32, etc.) associated with each of the six nodes. Each weight is sequentially assigned according to the positions of neighboring nodes.
  • the right side of FIG. 7 shows the neighboring node pattern values.
  • the neighbor node pattern value is the sum of values multiplied by the weights of the ocupided neighbor nodes (neighbor nodes with points). Therefore, the neighbor node pattern values range from 0 to 63. When the value of the neighbor node pattern is 0, it indicates that there is no node (ocupid node) having a point among the neighboring nodes of the corresponding node. When the neighbor node pattern value is 63, it indicates that all of the neighboring nodes are ocupid nodes. As shown in the figure, since neighboring nodes to which weights 1, 2, 4, and 8 are assigned are ocupided nodes, the neighboring node pattern value is 15, which is the sum of 1, 2, 4, and 8.
  • the point cloud encoder may perform coding according to the value of the neighboring node pattern (for example, if the value of the neighboring node pattern is 63, 64 types of coding are performed). According to embodiments, the point cloud encoder may change the neighbor node pattern value (eg, based on a table that changes 64 to 10 or 6) to reduce coding complexity.
  • the encoded geometry is reconstructed (decompressed) before attribute encoding is performed.
  • the geometry reconstruction operation may include changing the arrangement of the direct coded points (eg, placing the direct coded points in front of the point cloud data).
  • the geometry reconstruction process is triangular reconstruction, upsampling, and voxelization. Since the attribute is dependent on the geometry, the attribute encoding is performed based on the reconstructed geometry.
  • the point cloud encoder may reorganize the points by LOD.
  • the figure shows the point cloud content corresponding to the LOD.
  • the left side of the figure shows the original point cloud content.
  • the second figure from the left of the figure shows the distribution of points with the lowest LOD, and the rightmost figure of the figure shows the distribution of the points with the highest LOD. That is, the points of the lowest LOD are sparsely distributed, and the points of the highest LOD are densely distributed. That is, as the LOD increases according to the direction of the arrow indicated at the bottom of the drawing, the interval (or distance) between the points becomes shorter.
  • the point cloud content providing system or the point cloud encoder (for example, the point cloud video encoder 10002, the point cloud encoder of FIG. 4, or the LOD generator 40009) generates an LOD. can do.
  • the LOD is created by reorganizing the points into a set of refinement levels according to a set LOD distance value (or set of Euclidean Distance).
  • the LOD generation process is performed not only in the point cloud encoder but also in the point cloud decoder.
  • FIG. 9 shows examples (P0 to P9) of points of point cloud content distributed in a three-dimensional space.
  • the original order of FIG. 9 indicates the order of points P0 to P9 before LOD generation.
  • the LOD based order of FIG. 9 indicates the order of points according to the LOD generation. Points are rearranged by LOD. Also, the high LOD includes points belonging to the low LOD.
  • LOD0 includes P0, P5, P4 and P2.
  • LOD1 includes the points of LOD0 and P1, P6 and P3.
  • LOD2 includes points of LOD0, points of LOD1, and P9, P8 and P7.
  • the point cloud encoder may perform predictive transform coding, lifting transform coding, and RAHT transform coding selectively or in combination.
  • a point cloud encoder may generate predictors for points and perform predictive transform coding to set a predictive attribute (or predictive attribute value) of each point. That is, N predictors may be generated for N points.
  • the prediction attribute (or attribute value) is a weight calculated based on the distance to each neighboring point in the attributes (or attribute values, for example, color, reflectance, etc.) of neighboring points set in the predictor of each point (or the weight value) is set as the average value of the multiplied value.
  • the point cloud encoder for example, the coefficient quantization unit 40011 according to the embodiments subtracts the predicted attribute (attribute value) from the attribute (attribute value) of each point (residuals, residual attribute, residual attribute value, attribute quantization and inverse quantization can be performed on the prediction residual value, etc.
  • the quantization process is shown in the following table.
  • the point cloud encoder (for example, the arithmetic encoder 40012) according to the embodiments may entropy-code the quantized and dequantized residual values as described above when there are points adjacent to the predictor of each point.
  • the point cloud encoder according to the examples (eg, the arithmetic encoder 40012) may entropy-code the attributes of the corresponding point without performing the above-described process if there are no neighboring points in the predictor of each point.
  • the point cloud encoder (eg, the lifting transform unit 40010) generates a predictor of each point, sets the LOD calculated in the predictor, registers neighboring points, and weights according to the distance to the neighboring points
  • Lifting transform coding may be performed by setting .Lifting transform coding according to embodiments is similar to the aforementioned predictive transform coding, except that a weight is accumulated and applied to an attribute value.
  • the process of cumulatively applying weights to values is as follows.
  • the weights calculated for all predictors are additionally multiplied by the weights stored in the QW corresponding to the predictor index, and the calculated weights are cumulatively added to the update weight array as the indexes of neighboring nodes.
  • the value obtained by multiplying the calculated weight by the attribute value of the index of the neighbor node is accumulated and summed.
  • predictive attribute values are calculated by additionally multiplying the attribute values updated through the lift update process by the weights updated through the lift prediction process (stored in QW).
  • a point cloud encoder eg, the coefficient quantization unit 40011
  • a point cloud encoder eg, arithmetic encoder 40012
  • entropy codes the quantized attribute values.
  • the point cloud encoder (for example, the RAHT transform unit 40008) according to the embodiments may perform RAHT transform coding for estimating the attributes of the nodes of the higher level by using the attributes associated with the nodes at the lower level of the octree.
  • RAHT transform coding is an example of attribute intra coding with octree backward scan.
  • the point cloud encoder according to the embodiments scans the entire area from the voxel, and repeats the merging process up to the root node while merging the voxels into a larger block at each step.
  • the merging process according to the embodiments is performed only for the ocupid node. A merging process is not performed on an empty node, and a merging process is performed on a node immediately above the empty node.
  • g lx, y, and z represent the average attribute values of voxels in level l.
  • g lx, y, z can be calculated from g l+1 2x, y, z and g l+1 2x+1, y, z .
  • g l-1 x, y, z are low-pass values, which are used in the merging process at the next higher level.
  • h l-1 x, y, and z are high-pass coefficients, and the high-pass coefficients in each step are quantized and entropy-coded (eg, encoding of the arithmetic encoder 400012 ).
  • the root node is created as follows through the last g 1 0, 0, 0 and g 1 0, 0, 1 ,
  • FIG. 10 shows an example of a point cloud decoder according to embodiments.
  • the point cloud decoder shown in FIG. 10 is an example of the point cloud video decoder 10006 described in FIG. 1 , and may perform the same or similar operations to the operation of the point cloud video decoder 10006 described in FIG. 1 .
  • the point cloud decoder may receive a geometry bitstream and an attribute bitstream included in one or more bitstreams.
  • the point cloud decoder includes a geometry decoder and an attribute decoder.
  • the geometry decoder outputs decoded geometry by performing geometry decoding on the geometry bitstream.
  • the attribute decoder outputs decoded attributes by performing attribute decoding based on the decoded geometry and the attribute bitstream.
  • the decoded geometry and decoded attributes are used to reconstruct the point cloud content (decoded point cloud).
  • FIG. 11 shows an example of a point cloud decoder according to embodiments.
  • the point cloud decoder shown in FIG. 11 is an example of the point cloud decoder described with reference to FIG. 10 , and may perform a decoding operation that is a reverse process of the encoding operation of the point cloud encoder described with reference to FIGS. 1 to 9 .
  • the point cloud decoder may perform geometry decoding and attribute decoding. Geometry decoding is performed before attribute decoding.
  • a point cloud decoder may include an arithmetic decoder 11000, a synthesize octree 11001, a synthesize surface approximation 11002, and a reconstruct geometry , 11003), inverse transform coordinates (11004), arithmetic decoder (11005), inverse quantize (11006), RAHT transform unit (11007), LOD generator (generate LOD, 11008) ), an inverse lifting unit (Inverse lifting, 11009), and / or a color inverse transform unit (inverse transform colors, 11010).
  • the arithmetic decoder 11000 , the octree synthesizer 11001 , the surface opproximation synthesizer 11002 , the geometry reconstruction unit 11003 , and the coordinate system inverse transformation unit 11004 may perform geometry decoding.
  • Geometry decoding according to embodiments may include direct coding and trisoup geometry decoding. Direct coding and trisup geometry decoding are optionally applied. Also, the geometry decoding is not limited to the above example, and is performed as a reverse process of the geometry encoding described with reference to FIGS. 1 to 9 .
  • the arithmetic decoder 11000 decodes the received geometry bitstream based on arithmetic coding.
  • the operation of the arithmetic decoder 11000 corresponds to the reverse process of the arithmetic encoder 40004 .
  • the octree synthesizer 11001 may generate an octree by obtaining an occupanci code from a decoded geometry bitstream (or information about a geometry obtained as a result of decoding).
  • a detailed description of the occupanci code is the same as described with reference to FIGS. 1 to 9 .
  • the surface op-proximation synthesizing unit 11002 may synthesize a surface based on a decoded geometry and/or a generated octree when trisupe geometry encoding is applied.
  • the geometry reconstruction unit 11003 may regenerate the geometry based on the surface and/or the decoded geometry. As described with reference to FIGS. 1 to 9 , direct coding and tri-soup geometry encoding are selectively applied. Accordingly, the geometry reconstruction unit 11003 directly brings and adds position information of points to which direct coding is applied. In addition, when tri-soup geometry encoding is applied, the geometry reconstruction unit 11003 may perform a reconstruction operation of the geometry reconstruction unit 40005, for example, triangle reconstruction, up-sampling, and voxelization to restore the geometry. have. Specific details are the same as those described with reference to FIG. 6 and thus will be omitted.
  • the reconstructed geometry may include a point cloud picture or frame that does not include attributes.
  • the coordinate system inverse transform unit 11004 may obtain positions of points by transforming the coordinate system based on the restored geometry.
  • the arithmetic decoder 11005, the inverse quantization unit 11006, the RAHT transform unit 11007, the LOD generator 11008, the inverse lifting unit 11009, and/or the color inverse transform unit 11010 are the attributes described with reference to FIG. decoding can be performed.
  • Attribute decoding according to embodiments includes Region Adaptive Hierarchical Transform (RAHT) decoding, Interpolaration-based hierarchical nearest-neighbor prediction-Prediction Transform decoding, and interpolation-based hierarchical nearest-neighbor prediction with an update/lifting step (Lifting Transform)) decoding may be included.
  • RAHT Region Adaptive Hierarchical Transform
  • Interpolaration-based hierarchical nearest-neighbor prediction-Prediction Transform decoding Interpolaration-based hierarchical nearest-neighbor prediction-Prediction Transform decoding
  • interpolation-based hierarchical nearest-neighbor prediction with an update/lifting step (Lifting Transform)) decoding may be included.
  • the arithmetic decoder 11005 decodes an attribute bitstream by arithmetic coding.
  • the inverse quantization unit 11006 inverse quantizes the decoded attribute bitstream or information about the attribute secured as a result of decoding, and outputs inverse quantized attributes (or attribute values). Inverse quantization may be selectively applied based on attribute encoding of the point cloud encoder.
  • the RAHT transformation unit 11007, the LOD generation unit 11008, and/or the inverse lifting unit 11009 may process the reconstructed geometry and dequantized attributes. As described above, the RAHT conversion unit 11007, the LOD generation unit 11008, and/or the inverse lifting unit 11009 may selectively perform a corresponding decoding operation according to the encoding of the point cloud encoder.
  • the color inverse transform unit 11010 performs inverse transform coding for inverse transforming color values (or textures) included in decoded attributes.
  • the operation of the color inverse transform unit 11010 may be selectively performed based on the operation of the color transform unit 40006 of the point cloud encoder.
  • the elements of the point cloud decoder of FIG. 11 are not shown in the figure, hardware including one or more processors or integrated circuits configured to communicate with one or more memories included in the point cloud providing apparatus , software, firmware, or a combination thereof.
  • the one or more processors may perform at least any one or more of the operations and/or functions of the elements of the point cloud decoder of FIG. 11 described above.
  • the one or more processors may operate or execute a set of software programs and/or instructions for performing operations and/or functions of the elements of the point cloud decoder of FIG. 11 .
  • the transmission device shown in FIG. 12 is an example of the transmission device 10000 of FIG. 1 (or the point cloud encoder of FIG. 4 ).
  • the transmitting apparatus shown in FIG. 12 may perform at least any one or more of the same or similar operations and methods to the operations and encoding methods of the point cloud encoder described with reference to FIGS. 1 to 9 .
  • the transmission apparatus includes a data input unit 12000 , a quantization processing unit 12001 , a voxelization processing unit 12002 , an octree occupancy code generation unit 12003 , a surface model processing unit 12004 , and an intra/ Inter-coding processing unit 12005, arithmetic coder 12006, metadata processing unit 12007, color conversion processing unit 12008, attribute conversion processing unit (or attribute conversion processing unit) 12009, prediction/lifting/RAHT conversion It may include a processing unit 12010 , an arithmetic coder 12011 , and/or a transmission processing unit 12012 .
  • the data input unit 12000 receives or acquires point cloud data.
  • the data input unit 12000 may perform the same or similar operation and/or acquisition method to the operation and/or acquisition method of the point cloud video acquisition unit 10001 (or the acquisition process 20000 described in FIG. 2 ).
  • the coder 12006 performs geometry encoding. Since the geometry encoding according to the embodiments is the same as or similar to the geometry encoding described with reference to FIGS. 1 to 9 , a detailed description thereof will be omitted.
  • the quantization processing unit 12001 quantizes a geometry (eg, a position value or a position value of points).
  • the operation and/or quantization of the quantization processing unit 12001 is the same as or similar to the operation and/or quantization of the quantization unit 40001 described with reference to FIG. 4 .
  • a detailed description is the same as that described with reference to FIGS. 1 to 9 .
  • the voxelization processing unit 12002 voxelizes position values of quantized points.
  • the voxelization processing unit 12002 may perform the same or similar operations and/or processes as those of the quantization unit 40001 described with reference to FIG. 4 and/or the voxelization process. A detailed description is the same as that described with reference to FIGS. 1 to 9 .
  • the octree occupancy code generator 12003 performs octree coding on the positions of voxelized points based on the octree structure.
  • the octree occupanci code generator 12003 may generate an occupanci code.
  • the octree occupancy code generator 12003 may perform the same or similar operations and/or methods to those of the point cloud encoder (or the octree analyzer 40002) described with reference to FIGS. 4 and 6 . A detailed description is the same as that described with reference to FIGS. 1 to 9 .
  • the surface model processing unit 12004 may perform tri-supply geometry encoding by reconstructing positions of points in a specific region (or node) based on a voxel based on a surface model.
  • the fore surface model processing unit 12004 may perform the same or similar operations and/or methods as those of the point cloud encoder (eg, the surface appropriation analyzer 40003) described with reference to FIG. 4 .
  • a detailed description is the same as that described with reference to FIGS. 1 to 9 .
  • the intra/inter coding processing unit 12005 may perform intra/inter coding of point cloud data.
  • the intra/inter coding processing unit 12005 may perform the same or similar coding to the intra/inter coding described with reference to FIG. 7 . A detailed description is the same as that described with reference to FIG. 7 .
  • the intra/inter coding processing unit 12005 may be included in the arithmetic coder 12006 .
  • the arithmetic coder 12006 entropy encodes an octree and/or an approximated octree of point cloud data.
  • the encoding method includes an arithmetic encoding method.
  • the arithmetic coder 12006 performs the same or similar operations and/or methods as the operations and/or methods of the arithmetic encoder 40004 .
  • the metadata processing unit 12007 processes metadata related to point cloud data, for example, a setting value, and provides it to necessary processing such as geometry encoding and/or attribute encoding. Also, the metadata processing unit 12007 according to embodiments may generate and/or process signaling information related to geometry encoding and/or attribute encoding. Signaling information according to embodiments may be encoded separately from geometry encoding and/or attribute encoding. Also, signaling information according to embodiments may be interleaved.
  • the color conversion processing unit 12008, the attribute conversion processing unit 12009, the prediction/lifting/RAHT conversion processing unit 12010, and the arithmetic coder 12011 perform attribute encoding. Since the attribute encoding according to the embodiments is the same as or similar to the attribute encoding described with reference to FIGS. 1 to 9 , a detailed description thereof will be omitted.
  • the color conversion processing unit 12008 performs color conversion coding for converting color values included in attributes.
  • the color conversion processing unit 12008 may perform color conversion coding based on the reconstructed geometry.
  • the description of the reconstructed geometry is the same as described with reference to FIGS. 1 to 9 .
  • the same or similar operation and/or method to the operation and/or method of the color conversion unit 40006 described with reference to FIG. 4 is performed. A detailed description will be omitted.
  • the attribute transformation processing unit 12009 performs attribute transformation for transforming attributes based on positions and/or reconstructed geometry to which geometry encoding has not been performed.
  • the attribute transformation processing unit 12009 performs the same or similar operations and/or methods to those of the attribute transformation unit 40007 described in FIG. 4 .
  • a detailed description will be omitted.
  • the prediction/lifting/RAHT transform processing unit 12010 may code the transformed attributes by any one or a combination of RAHT coding, predictive transform coding, and lifting transform coding.
  • the prediction/lifting/RAHT transformation processing unit 12010 performs at least one or more of the same or similar operations to the operations of the RAHT transformation unit 40008, the LOD generation unit 40009, and the lifting transformation unit 40010 described in FIG. 4 . do.
  • the descriptions of predictive transform coding, lifting transform coding, and RAHT transform coding are the same as those described with reference to FIGS. 1 to 9 , a detailed description thereof will be omitted.
  • the arithmetic coder 12011 may encode coded attributes based on arithmetic coding.
  • the arithmetic coder 12011 performs the same or similar operations and/or methods to the operations and/or methods of the arithmetic encoder 400012 .
  • the transmission processing unit 12012 transmits each bitstream including the encoded geometry and/or encoded attribute and metadata information, or converts the encoded geometry and/or the encoded attribute and metadata information into one It can be configured as a bitstream and transmitted.
  • the bitstream may include one or more sub-bitstreams.
  • the bitstream according to the embodiments is a Sequence Parameter Set (SPS) for signaling of a sequence level, a Geometry Parameter Set (GPS) for signaling of the geometry information coding, an Attribute Parameter Set (APS) for signaling of the attribute information coding, a tile It may include signaling information including a tile parameter set (TPS) for level signaling and slice data.
  • SPS Sequence Parameter Set
  • GPS Geometry Parameter Set
  • APS Attribute Parameter Set
  • TPS tile parameter set
  • Slice data may include information about one or more slices.
  • One slice according to embodiments may include one geometry bitstream (Geom00) and one or more attribute bitstreams (Attr00, Attr10).
  • a slice refers to a series of syntax elements representing all or a part of a coded point cloud frame.
  • the TPS may include information about each tile (eg, coordinate value information and height/size information of a bounding box, etc.) for one or more tiles.
  • a geometry bitstream may include a header and a payload.
  • the header of the geometry bitstream according to the embodiments may include identification information (geom_parameter_set_id), a tile identifier (geom_tile_id), a slice identifier (geom_slice_id) of a parameter set included in GPS, and information about data included in a payload.
  • the metadata processing unit 12007 may generate and/or process signaling information and transmit it to the transmission processing unit 12012 .
  • elements performing geometry encoding and elements performing attribute encoding may share data/information with each other as dotted lines are processed.
  • the transmission processing unit 12012 may perform the same or similar operation and/or transmission method to the operation and/or transmission method of the transmitter 10003 . Since the detailed description is the same as that described with reference to FIGS. 1 to 2 , a detailed description thereof will be omitted.
  • FIG. 13 is an example of a receiving apparatus according to embodiments.
  • the receiving device shown in FIG. 13 is an example of the receiving device 10004 of FIG. 1 (or the point cloud decoder of FIGS. 10 and 11 ).
  • the receiving apparatus shown in FIG. 13 may perform at least any one or more of the same or similar operations and methods to the operations and decoding methods of the point cloud decoder described with reference to FIGS. 1 to 11 .
  • the reception apparatus includes a reception unit 13000 , a reception processing unit 13001 , an arithmetic decoder 13002 , an Occupancy code-based octree reconstruction processing unit 13003 , and a surface model processing unit (triangle reconstruction). , up-sampling, voxelization) 13004, inverse quantization processing unit 13005, metadata parser 13006, arithmetic decoder 13007, inverse quantization processing unit 13008, prediction It may include a /lifting/RAHT inverse transformation processing unit 13009 , an inverse color transformation processing unit 13010 , and/or a renderer 13011 .
  • Each component of decoding according to embodiments may perform a reverse process of a component of encoding according to embodiments.
  • the receiver 13000 receives point cloud data.
  • the receiver 13000 may perform the same or similar operation and/or reception method as the operation and/or reception method of the receiver 10005 of FIG. 1 . A detailed description will be omitted.
  • the reception processing unit 13001 may acquire a geometry bitstream and/or an attribute bitstream from the received data.
  • the reception processing unit 13001 may be included in the reception unit 13000 .
  • the arithmetic decoder 13002, the occupancy code-based octree reconstruction processing unit 13003, the surface model processing unit 13004, and the inverse quantization processing unit 13005 may perform geometry decoding. Since the geometry decoding according to the embodiments is the same as or similar to the geometry decoding described with reference to FIGS. 1 to 10 , a detailed description thereof will be omitted.
  • the arithmetic decoder 13002 may decode a geometry bitstream based on arithmetic coding.
  • the arithmetic decoder 13002 performs the same or similar operation and/or coding to the operation and/or coding of the arithmetic decoder 11000 .
  • the occupancy code-based octree reconstruction processing unit 13003 may reconstruct the octopus by acquiring an occupanci code from a decoded geometry bitstream (or information about a geometry secured as a result of decoding).
  • the occupancy code-based octree reconstruction processing unit 13003 performs the same or similar operations and/or methods as those of the octree synthesis unit 11001 and/or the octree generation method.
  • the surface model processing unit 13004 may decode a trichop geometry based on a surface model method and reconstruct a geometry related thereto (eg, triangle reconstruction, up-sampling, voxelization) based on the surface model method when trisoop geometry encoding is applied. can be performed.
  • the surface model processing unit 13004 performs the same or similar operations to the operations of the surface op-proximation synthesizing unit 11002 and/or the geometry reconstruction unit 11003 .
  • the inverse quantization processing unit 13005 may inverse quantize the decoded geometry.
  • the metadata parser 13006 may parse metadata included in the received point cloud data, for example, a setting value.
  • the metadata parser 13006 may pass the metadata to geometry decoding and/or attribute decoding. A detailed description of the metadata is the same as that described with reference to FIG. 12 , and thus will be omitted.
  • the arithmetic decoder 13007 , the inverse quantization processing unit 13008 , the prediction/lifting/RAHT inverse transformation processing unit 13009 , and the color inverse transformation processing unit 13010 perform attribute decoding. Since the attribute decoding is the same as or similar to the attribute decoding described with reference to FIGS. 1 to 10 , a detailed description thereof will be omitted.
  • the arithmetic decoder 13007 may decode an attribute bitstream by arithmetic coding.
  • the arithmetic decoder 13007 may perform decoding of the attribute bitstream based on the reconstructed geometry.
  • the arithmetic decoder 13007 performs the same or similar operation and/or coding to the operation and/or coding of the arithmetic decoder 11005 .
  • the inverse quantization processing unit 13008 may inverse quantize the decoded attribute bitstream.
  • the inverse quantization processing unit 13008 performs the same or similar operations and/or methods as those of the inverse quantization unit 11006 and/or the inverse quantization method.
  • the prediction/lifting/RAHT inverse transform processing unit 13009 may process the reconstructed geometry and inverse quantized attributes.
  • the prediction/lifting/RAHT inverse transform processing unit 13009 performs the same or similar operations and/or decodings as the operations and/or decodings of the RAHT transform unit 11007, the LOD generation unit 11008 and/or the inverse lifting unit 11009 and/or At least any one or more of the decodings are performed.
  • the color inverse transform processing unit 13010 according to embodiments performs inverse transform coding for inverse transforming color values (or textures) included in decoded attributes.
  • the color inverse transform processing unit 13010 performs the same or similar operation and/or inverse transform coding to the operation and/or inverse transform coding of the inverse color transform unit 11010 .
  • the renderer 13011 may render point cloud data.
  • FIG. 14 shows an example of a structure capable of interworking with a method/device for transmitting and receiving point cloud data according to embodiments.
  • the structure of FIG. 14 includes at least one or more of a server 1460 , a robot 1410 , an autonomous vehicle 1420 , an XR device 1430 , a smartphone 1440 , a home appliance 1450 , and/or an HMD 1470 .
  • a configuration connected to the cloud network 1410 is shown.
  • the robot 1410 , the autonomous driving vehicle 1420 , the XR device 1430 , the smart phone 1440 , or the home appliance 1450 are referred to as devices.
  • the XR device 1430 may correspond to a point cloud data (PCC) device according to embodiments or may be linked with the PCC device.
  • PCC point cloud data
  • the cloud network 1400 may refer to a network that constitutes a part of the cloud computing infrastructure or exists in the cloud computing infrastructure.
  • the cloud network 1400 may be configured using a 3G network, a 4G or Long Term Evolution (LTE) network, or a 5G network.
  • LTE Long Term Evolution
  • the server 1460 includes at least one of a robot 1410 , an autonomous vehicle 1420 , an XR device 1430 , a smartphone 1440 , a home appliance 1450 and/or an HMD 1470 , and a cloud network 1400 . It is connected through and may help at least a part of the processing of the connected devices 1410 to 1470 .
  • a Head-Mount Display (HMD) 1470 represents one of the types in which an XR device and/or a PCC device according to embodiments may be implemented.
  • the HMD-type device according to the embodiments includes a communication unit, a control unit, a memory unit, an I/O unit, a sensor unit, a power supply unit, and the like.
  • the devices 1410 to 1450 shown in FIG. 14 may be linked/coupled with the point cloud data transmission/reception device according to the above-described embodiments.
  • XR / PCC device 1430 is PCC and / or XR (AR + VR) technology is applied, HMD (Head-Mount Display), HUD (Head-Up Display) provided in the vehicle, television, mobile phone, smart phone, It may be implemented as a computer, a wearable device, a home appliance, a digital signage, a vehicle, a stationary robot, or a mobile robot.
  • HMD Head-Mount Display
  • HUD Head-Up Display
  • the XR/PCC device 1430 analyzes three-dimensional point cloud data or image data acquired through various sensors or from an external device to generate position data and attribute data for three-dimensional points in the surrounding space or real objects. Information can be obtained, and the XR object to be output can be rendered and output. For example, the XR/PCC apparatus 1430 may output an XR object including additional information on the recognized object in correspondence with the recognized object.
  • the XR/PCC device 1430 may be implemented as a mobile phone 1440 or the like to which PCC technology is applied.
  • the mobile phone 1440 may decode and display the point cloud content based on the PCC technology.
  • the autonomous driving vehicle 1420 may be implemented as a mobile robot, a vehicle, an unmanned aerial vehicle, etc. by applying PCC technology and XR technology.
  • the autonomous driving vehicle 1420 to which the XR/PCC technology is applied may refer to an autonomous driving vehicle equipped with a means for providing an XR image, an autonomous driving vehicle subject to control/interaction within the XR image, or the like.
  • the autonomous driving vehicle 1420 that is the target of control/interaction in the XR image may be distinguished from the XR device 1430 and may be interlocked with each other.
  • the autonomous vehicle 1420 having means for providing an XR/PCC image may obtain sensor information from sensors including a camera, and output an XR/PCC image generated based on the acquired sensor information.
  • the autonomous vehicle 1420 may provide the occupant with an XR/PCC object corresponding to a real object or an object in a screen by having a HUD and outputting an XR/PCC image.
  • the XR/PCC object when the XR/PCC object is output to the HUD, at least a portion of the XR/PCC object may be output to overlap the real object toward which the passenger's gaze is directed.
  • the XR/PCC object when the XR/PCC object is output to a display provided inside the autonomous vehicle, at least a part of the XR/PCC object may be output to overlap the object in the screen.
  • the autonomous vehicle 1220 may output XR/PCC objects corresponding to objects such as a lane, other vehicles, traffic lights, traffic signs, two-wheeled vehicles, pedestrians, and buildings.
  • VR Virtual Reality
  • AR Augmented Reality
  • MR Magnetic Reality
  • PCC Point Cloud Compression
  • VR technology is a display technology that provides only CG images of objects or backgrounds in the real world.
  • AR technology refers to a technology that shows a virtual CG image on top of a real object image.
  • MR technology is similar to the aforementioned AR technology in that it shows virtual objects by mixing and combining them in the real world.
  • real objects and virtual objects made of CG images are clear, and virtual objects are used in a form that complements real objects, whereas in MR technology, virtual objects are regarded as having the same characteristics as real objects. distinct from technology. More specifically, for example, a hologram service to which the above-described MR technology is applied.
  • VR, AR, and MR technologies are sometimes called XR (extended reality) technologies rather than clearly distinguishing them. Accordingly, embodiments of the present invention are applicable to all of VR, AR, MR, and XR technologies.
  • encoding/decoding based on PCC, V-PCC, and G-PCC technology may be applied.
  • the PCC method/apparatus according to the embodiments may be applied to a vehicle providing an autonomous driving service.
  • a vehicle providing an autonomous driving service is connected to a PCC device to enable wired/wireless communication.
  • the point cloud data (PCC) transceiver receives/processes AR/VR/PCC service-related content data that can be provided together with the autonomous driving service when connected to a vehicle to enable wired/wireless communication, can be sent to
  • the point cloud transceiver device may receive/process AR/VR/PCC service related content data according to a user input signal input through the user interface device and provide it to the user.
  • a vehicle or a user interface device may receive a user input signal.
  • a user input signal according to embodiments may include a signal indicating an autonomous driving service.
  • a method/apparatus for transmitting point cloud data is a transmitting apparatus 10000 of FIG. 1 , a point cloud video encoder 10002 , a transmitter 10003 , and an acquisition-encoding-transmitting (20000-20001-20002) of FIG. 2 . , the encoder of FIG. 4 , the transmitter of FIG. 12 , the device of FIG. 14 , the encoder of FIG. 21 , and the like.
  • a method/apparatus for receiving point cloud data is a receiving device 10004, a receiver 10005, a point cloud video decoder 10006 of FIG. 1, and a transmission-decoding-rendering (20002-20003-20004) of FIG. , the decoder of Figs. 10-11, the receiver of Fig. 13, the device of Fig. 14, the decoder of Fig. 22, and the like.
  • the method/device for transmitting and receiving point cloud data according to the embodiments may be abbreviated as a method/device according to the embodiments.
  • geometry data, geometry information, location information, and the like constituting point cloud data are interpreted to have the same meaning.
  • Attribute data, attribute information, attribute information, and the like constituting point cloud data are interpreted to have the same meaning.
  • Point cloud data transmission and reception method / device is a predictive tree configuration extension method for low-latency 3D map point cloud geometry information compression (A method to build predictive geometry tree for low-latency geometry coding of 3D map point cloud) can provide
  • Geometry-based Point Cloud Compression For efficient geometry compression of G-PCC, a method of constructing a predictive tree may be supported. For example, it may include an origin selection method and a signaling method, a laser angle-based alignment method for generating a prediction tree, and/or a fast prediction tree construction method, and the like.
  • Embodiments relate to a method for increasing the compression efficiency of Geometry-based Point Cloud Compression (G-PCC) for 3D point cloud data compression.
  • G-PCC Geometry-based Point Cloud Compression
  • a point cloud is composed of a set of points, and each point may have geometry information and attribute information.
  • the geometry information is three-dimensional position (XYZ) information
  • the attribute information is a color (RGB, YUV, etc.) and/or a reflection value.
  • the G-PCC decoding process receives a geometry bitstream and an attribute bitstream of an encoded slice unit, decodes the geometry, and decodes attribute information based on the geometry reconstructed through the decoding process.
  • An octree-based, predictive tree-based, or trisoup-based compression technique may be used for geometric information compression.
  • the method/apparatus for transmitting and receiving point cloud data may perform a prediction tree-based geometry compression technique to increase the geometry compression efficiency of 3D map content captured by a lidar device.
  • the position coordinates of the reflector can be measured by emitting a laser pulse and measuring the time it takes to reflect and return.
  • Depth information can be extracted through lidar equipment using such a radar system.
  • the point cloud content generated through the lidar device may consist of several frames, or may integrate several frames into one content.
  • 3D map point cloud content may refer to data generated by capturing multiple frames with lidar equipment and integrating them into one content.
  • the angular characteristics that appear in the data captured by the lidar equipment that is, the angle When changing to , the rule between points may be hidden, and applying an angle mode to it may not be more efficient than compression based on the Cartesian coordinate system.
  • the prediction tree-based geometry compression method applied to the 3D map point cloud content cannot increase the compression efficiency by using the angle mode, and a method for increasing the compression efficiency from the regularity of the points in the content may be required.
  • the prediction tree can be performed by predicting the position of the current point through the vectors of the parent nodes, the residual value of the predicted point and the current point becomes smaller depending on whether the parent node with regularity is selected well, so that the bitstream size can reduce
  • Embodiments intend to support a prediction tree construction method for supporting efficient geometry compression based on prediction tree of 3D map data captured through lidar equipment and integrated into one content.
  • the prediction tree construction according to the embodiments may be performed in the geometry encoder of the PCC encoder and may be reconstructed through a geometry decoding process of the PCC decoder.
  • 15 illustrates additional attribute data of point cloud data according to embodiments.
  • Point cloud data compressed and restored by the decoder of FIG. 11 , the receiving apparatus of FIG. 13 , the device of FIG. 14 , and the decoder of FIG. 22 may have properties as shown in FIG. 15 .
  • the origin position selection method When there is a laser angle value according to the embodiments, the origin position selection method:
  • the point cloud captured by the lidar with 3D map data captured through the lidar equipment and integrated into one content is the position (x, y, z), properties (red, green, blue, reflectance) ) value, it may have additional attribute data such as time, laser angle, and normal position (nx, ny, nz).
  • FIG 16 shows an example of an origin position with respect to point cloud data according to embodiments.
  • the decoder of FIG. 11 , the receiving device of FIG. 13 , the device of FIG. 14 , the decoder of FIG. 22 , etc. may perform compression/restore by setting the origin of point cloud data and point cloud data configured in the form of a 3D map.
  • the positions of the left, bottom, and front of the bounding box of the slice can be set as the position of the origin (16000).
  • the position of the origin can affect the point alignment process to generate the prediction tree
  • the sorted shape can affect the construction of the prediction tree
  • the prediction tree affects the prediction value, so the residual value with the prediction value is affected. may affect the bitstream size.
  • a point of the bounding box corresponding to slice 0 may be processed as the origin.
  • the origin of the bounding box corresponding to slice 1 may be the left/bottom/front position of the bounding box.
  • FIG 17 shows an example of an origin position according to embodiments.
  • the method/apparatus may calculate the origin position in the slice through the following process.
  • a candidate angle value (origin_laser_angle) corresponding to the origin can be input.
  • 90° may be a candidate angle value.
  • the position (origin_direction) of the point corresponding to the origin can be input.
  • the left may be the position of the point.
  • the origin position value can be set as the origin position value according to the origin_direction by comparing the position value of p with the position value of origin.
  • origin_direction is left and origin.x > p.x
  • p may be set as the origin location value. This is because p is located further to the left of origin.
  • the method/apparatus according to the embodiments may transform coordinates for points in order to set the position of the origin. It changes from the Cartesian coordinate system to the spherical coordinate system based on the origin.
  • Coordinate system transformation is 1) also used when applying angular mode of predictive geom coding, and 2) point alignment in normal mode and/or angular mode of predictive geom. To transform and align the coordinate values.
  • the (x, y, z) Cartesian coordinates are changed to azimuth, radius, and elevation (laser ID).
  • the origin is above the road Since it is displaced, a suitable azimuth and radius can be found.
  • a location 17002 where a set of points starts may correspond to a road area.
  • the origins 16000 and 17001 of the left/bottom/front of the bounding box are separated from the road area 17002, which is the basis for the arrangement of the points.
  • the position of the origin set based on the additional attribute data is set as the road starting point 17002 .
  • the origin position in the slice can be calculated through the following process.
  • a reference axis may be input.
  • the x-axis may be a reference axis.
  • a second reference axis may be input.
  • it could be the y-axis.
  • a vector range may be input. For example, you can set the range -0.2 to -1.
  • the position of the origin when it belongs to the vector range may be set.
  • the origin can be set to left/top/front.
  • the position of the origin when it does not belong to the vector range may be input. For example, you can set the origin to left/bottom/front.
  • point L existing at the smallest value and point R existing at the largest value can be found.
  • In diff which is a normalized value of R-L value, it can be checked whether it corresponds to the vector range based on the second reference axis. If it belongs to the range, you can set the specified position as the origin.
  • left/top/front can be set as the origin. If it doesn't, you can set left/bottom/front to the origin.
  • the points are searched in a certain direction (18002, 18005, 18008) according to the reference axis and the vector range from the points (18001, 18004, 18007).
  • the origin can be set.
  • An arrangement method may be set according to characteristics of content. For example, in the case of content in the form of spinning data captured by LiDAR equipment, it may help to efficiently generate a prediction tree when sorted based on azimuth.
  • Points can be sorted by Morton code. Alternatively, azimus alignment may be more efficient. If the left/bottom/front of the bounding box is the origin, there may be a problem in that the error becomes too large because the angle difference of the azimuth between the points is large.
  • the sorted point order can affect the construction of the prediction tree, and since the prediction tree affects the prediction value, it affects the residual value with the prediction value, It can affect the stream size.
  • 19 shows an example of laser angle-based alignment according to embodiments.
  • the decoder of FIG. 11 , the receiving device of FIG. 13 , the device of FIG. 14 , the decoder of FIG. 22 , etc. may set the origin as shown in FIGS. 16-18 using the attribute of FIG. 15 , and align the points as shown in FIG. 19 .
  • the points may be aligned based on the laser angle, and the laser angles may be grouped for alignment. For example, a laser angle of 0-5 degrees can be viewed as the same laser angle and the order of the points can be arranged.
  • the alignment is based on the radius, and when the radius is the same or the radius groups are the same, the alignment can be done based on the elevation.
  • the point cloud content is the appearance of a road, and the points of the point cloud data may be as shown in FIG. 19 .
  • the method/apparatus according to the embodiments may set a point at which the laser angle is 90 degrees and the coordinate is to the left of the axis as the war point 1900 .
  • the points can be aligned based on the laser angle (19002).
  • the points may be aligned based on the radius (19003).
  • the method/apparatus may set a point 19005 where the laser angle is 90 degrees and the left side of the axis as the new origin. . And you can align the points based on the laser angle. Since the position of the origin is set as the starting point (19005) of the road, it is possible to align the points for objects on the road along the road in the order of the laser angle. If the laser angle values between the points are the same, you can align the points based on the radius.
  • the order of the aligned points has an aligned shape along the road, so errors can be effectively reduced in the process of encoding and decoding the points.
  • the method/device according to the embodiments may generate the prediction tree while selecting the closest prediction point as the parent node through the KD-Tree generation/search process. This process can take a significant amount of time to perform. In a scenario aimed at low-latency geometry compression, the KD-Tree-based prediction tree generation technique may cause execution time issues.
  • the origin position is selected based on the laser angle, and if the laser angle-based alignment is performed, the method of quickly constructing a prediction tree is applied without using KD-Tree. can do.
  • a process of generating a prediction tree may be as follows.
  • the latest point of the laser angle of point p If the latest point of the laser angle of point p exists, the latest point can be set as a parent node on the prediction tree of the current point. Again, the current point can be set as the latest value of the current laser angle.
  • the current point can be set as the latest point of the current laser angle. You can set the current point as the first point of the current laser angle.
  • 20 shows an example of generating a laser group and a prediction tree according to embodiments.
  • the second laser group 20001 is the current layer angle group, and the first laser angle group 20000 is the second laser angle group 20001 It may be a group of lasers that have been processed earlier.
  • the first point 20002 may be set as a root node.
  • the current point 20002 may be set as the latest point of the current laser angle.
  • the current point 20002 may be set as the first point of the current laser angle.
  • the latest point 20002 of the laser angle of the point p(20003) may be set as a parent node on the prediction tree of the current point 20003.
  • the current point 20003 may be set as the latest value of the current laser angle.
  • point 20003 becomes the parent of point 20004.
  • the parent node of the first point 20002 of the current laser angle 20001 it can be set as the first point 20005 of the previous laser angle 20000.
  • the method/apparatus according to the embodiments may generate a fast prediction tree using points aligned based on a laser angle.
  • the latest point means a point located first among points included in a corresponding group and arranged.
  • points may be aligned based on a laser angle (a group according to an azimus value or an azimus range).
  • points are captured by the lidar, and the characteristics of the captured points may have strong regularity according to a radius and/or an azimuth value.
  • the latest point in the same laser angle group in FIG. 20 becomes the first point.
  • the range of group 20001 according to the laser angle (azimus) is 0 to 5 degrees, includes point 20002, and since point 20002 is the first point in the sorted order, it becomes a root node (point).
  • point 20005 is the first point, so it becomes a route. Accordingly, if there are groups and points according to a specific laser angle as described above, a parent/child relationship between points within a group may be set, and a parent/child relationship between groups may be set.
  • the acquisition unit (radia) according to the embodiments when the acquisition unit (radia) according to the embodiments is rotated to capture a point, there may be a difference for each azimuth angle in time, and when capturing in a flash type There may not be a difference in time because it is captured by many sensors in a specific area at once. If the meaning of the previous laser angle group according to the embodiments is grouped by Angle 0-5, 5-10, the 0-5 degree group may be viewed as the previous laser angle group based on the 5-10 degree group. Also, when the device according to the embodiments performs rotation and captures (spinning LiDAR, which is a common case), there may be a time difference.
  • 21 shows an apparatus for transmitting point cloud data according to embodiments.
  • Transmitting device 10000 in Fig. 1 point cloud video encoder 10002, transmitter 10003, Acquisition-encoding-transmitting (20000-20001-20002) in Fig. 2, Encoder in Fig. 4, Transmitting device in Fig. 12, Fig.
  • the device of 14 and the encoder of FIG. 21 are point cloud data transmission apparatuses according to embodiments corresponding to each other. Each component may correspond to hardware, software, a processor, and/or a combination thereof.
  • PCC data may be input and encoded as an input of the encoder to output a geometry information bitstream and an attribute information bitstream.
  • the data input unit may receive geometry data and attribute data.
  • the data input unit may receive a parameter setting value related to encoding.
  • the coordinate system transform unit may set the coordinate system associated with the position of the point of the geometric data as a system suitable for encoding.
  • the geometry information transformation quantization processing unit may transform and quantize the geometry data.
  • the spatial divider may divide the point cloud data into a spatial structure suitable for encoding.
  • the geometry information encoding unit When the geometry coding type is prediction-based coding, the geometry information encoding unit generates a prediction tree through the prediction tree generation unit, and performs a Rate Distortion Optimization (RDO) process based on the prediction tree generated through the prediction determiner to optimize the prediction mode.
  • RDO Rate Distortion Optimization
  • a geometry prediction value according to an optimal prediction mode may be generated.
  • the geometry information encoder may perform octree-based geometry coding through the octree generator, or may perform trichop-based geometry coding through the trichop generator.
  • the geometry position reconstruction unit may reconstruct the coded geometry data and provide it for attribute coding.
  • a geometry information bitstream may be configured by entropy-coding a residual value with a value predicted by the geometry information entropy encoder.
  • the prediction tree generator may receive a candidate angle value (origin_laser_angle) corresponding to the origin of the origin and a direction (origin_direction) of the point corresponding to the origin. From the received value, a point to be used as the origin in the slice can be selected according to the origin_laser_angle and origin_direction.
  • the origin value may be transmitted to the decoder as signal information.
  • the prediction tree generator may receive a method for sorting the points, and may sort the points according to the sorting method.
  • the point alignment method may include Morton code, radius, azimuth, elevation, sensor ID criteria, laser angle, or captured time sequence, and the like.
  • laser angle the order of points can be determined based on the selected origin.
  • the order of points is determined based on the radius or the same radius, and when the radius value is the same, the order of points can be determined based on the elevation.
  • the applied alignment method may be transmitted as signal information to the decoder.
  • the prediction tree generator may receive a prediction tree generation method, and may generate a prediction tree according to the received method.
  • the tree generation method may include an ordered order-based fast prediction tree generation method, a distance-based prediction tree generation method, and an angular-based prediction tree generation method. It can be selected according to the content characteristics and the type of service.
  • the applied prediction tree generation generation method may be transmitted to the decoder as signal information.
  • the prediction tree generator may receive a maximum distance value.
  • a prediction point list When a prediction point list is used, a neighboring prediction point for selecting a parent node is searched, and only when the distance to the searched points is smaller than the maximum distance value, it can be registered as a child node.
  • the maximum distance value can be input or set automatically through content analysis.
  • the geometry encoder for example, through the prediction tree generator, uses the additional attribute data of Fig. 15, selects the origin position as in Figs. 17-19, etc., aligns the points based on the laser angle, and makes a quick prediction from the points.
  • a tree can be created based on a group of laser angles. Predictive coding can be done by quickly establishing parent-child relationships from a fast prediction tree.
  • prediction geometry data for the current geometry data may be calculated through a fast prediction tree. By generating residual data between the current geometry data (original) and the prediction geometry data, a geometry bitstream including the residual data may be generated.
  • the attribute information encoder may encode the attribute data using the restored geometry data.
  • Information related to attribute information encoding may be delivered to the decoder as signaling information.
  • Fig. 21 shows a transmission method/apparatus (a point cloud data transmission method/apparatus) and a configuration (encoding process) of a point cloud data encoder according to the embodiments.
  • the prediction geometry coding of FIG. 21 may be an alternative to the octree-based scheme.
  • the predictive coding technique according to embodiments may support low latency and provide low complexity decoding.
  • the prediction (prediction) structure may be applied to, for example, content corresponding to category 3.
  • a prediction tree can be created by creating a prediction structure for the point cloud data.
  • a point in the point cloud data may correspond to a vertex of a tree.
  • Each vertex can be predicted from its ancestors in the tree.
  • Predictive geometry coding may perform prediction geometry coding using a tree structure. You can create a tree structure with parent/child between points.
  • the prediction mode may include No prediction, Delta prediction (i.e., p0), Linear prediction (i.e., 2p0-p1), Parallelogram predictor (i.e., 2p+p1-p2), and the like.
  • a prediction mode may be selected based on the RDO method.
  • a mode corresponding to a case in which a residual (residual) according to a prediction mode is smallest may be selected, and the used prediction mode (predictor) may be transmitted as signaling information.
  • FIG. 22 shows an apparatus for receiving point cloud data according to embodiments.
  • Receiver 10004, receiver 10005, point cloud video decoder 10006, transmit-decode-render (20002-20003-20004) in Fig. 2, decoder in Figs. 10-11, receiver in Fig. 13 , the device of FIG. 14, and the decoder of FIG. 22 are point cloud data receiving apparatuses according to embodiments.
  • Each component may correspond to hardware, software, a processor, and/or a combination thereof.
  • the reception operation of FIG. 22 may correspond to the transmission operation of FIG. 21 or a reverse process of the transmission operation may be performed.
  • the geometric information entropy decoding unit may entropy-decode the geometry data.
  • the octree reconstructor may reconstruct the geometry data based on the octree.
  • the prediction tree reconstruction unit may be used to receive and restore the prediction tree generation method, the origin position value, and the point alignment method, reconstruct the prediction tree accordingly, and decode the prediction value of the geometry.
  • the geometry decoder determines the position of the origin through the prediction tree reconstruction unit, identifies the point alignment method, predicts the geometry data through the fast prediction tree when fast prediction tree generation is applied, and adds it with the received residual geometry data. Geometry data can be restored.
  • the geometry position reconstruction unit may reconstruct the position of the geometry data and provide it to the attribute decoder.
  • the geometric information prediction unit may generate prediction data of the geometry data.
  • the geometric information transformation inverse quantization processing unit may inversely apply quantization to the geometry data based on the quantization parameter when the quantization is performed at the transmitting side.
  • the coordinate system inverse transform unit may inversely transform the coordinate system when the coordinate system related to the geometric data is transformed at the transmitting side.
  • the attribute information decoder may entropy-decode residual data of the attribute data from a bitstream including the attribute data through the attribute residual information entropy decoder.
  • the attribute information decoding unit may decode attribute data.
  • the residual attribution information inverse quantization processing unit may inversely quantize the residual attribution information based on the quantization parameter when quantized at the transmitting side. According to the transmission-side encoding method, the decoder may restore the attribute data.
  • the method/apparatus for receiving point cloud data may receive the bitstream in the order of the tree generated by the encoder, and may not perform the point alignment (coordinate transformation) process of the transmitting side.
  • the receiving method/device may reconstruct the prediction tree through the bitstream in the order in which it was received. In the process of reconstructing the prediction tree, origin information is used, and the finally reconstructed position can be converted into xyz coordinates through a coordinate conversion process.
  • FIG. 23 shows a bitstream including point cloud data and parameter information according to embodiments.
  • the point cloud data transmission apparatus generates the bitstream as shown in FIG. 23, and the point cloud data reception apparatus according to the embodiments such as FIG. 22 receives the bitstream as shown in FIG. 23 and receives the parameter information. Based on this, the point cloud data may be decoded.
  • the signaling information according to the embodiments may be used at a transmitting end or a receiving end.
  • the signaling information according to the embodiments is to be generated and transmitted by the transmission/reception device according to the embodiments, for example, a metadata processing unit (which may be referred to as a metadata generator, etc.) of the transmission device to be received and obtained by the metadata parser of the reception device.
  • a metadata processing unit which may be referred to as a metadata generator, etc.
  • Each operation of the receiving apparatus according to the embodiments may perform each operation based on signaling information.
  • the coded point cloud configuration is shown in FIG. 23 .
  • Each abbreviation means: Each abbreviation may be referred to by another term within the scope of the equivalent meaning.
  • SPS Sequence Parameter Set
  • GPS Geometry Parameter Set
  • APS Attribute Parameter Set
  • TPS Tile Parameter Set
  • Option information related to prediction tree generation may be added and signaled to SPS or GPS.
  • Option information related to prediction tree generation may be added to TPS or to the geometry header for each slice to signal.
  • a tile or slice is provided so that the point cloud can be divided into regions and processed.
  • different neighbor point set generation options are set for each region to provide a low-complexity and low-reliability result or, conversely, a high-complexity but high-reliability selection method. It can be set differently according to the processing capacity of the receiver.
  • the point cloud when the point cloud is divided into tiles, different options may be applied to each tile.
  • different options when the point cloud is divided into slices, different options may be applied to each slice.
  • Fig. 24 is a sequence parameter set included in the bitstream of Fig. 23;
  • the method/apparatus according to the embodiments may provide efficient signaling by including information related to prediction tree generation according to the embodiments in a sequence parameter set.
  • Profile indicates the profile that the bitstream conforms to as specified in Appendix A.
  • the bitstream may not include a profile_idc value that is not a value according to embodiments.
  • Other values of profile_idc may be reserved for future use in ISO/IEC.
  • Profile compatibility flag (profile_compatibility_flags): profile_compatibility_flags equal to 1 indicates that the bitstream conforms to the profile indicated by profile_idc equal to j.
  • the number of SPS attribute sets indicates the number of coded attributes in the bitstream.
  • the value of sps_num_attribute_sets may be between 0 and 63.
  • the attribute dimension indicates the number of components of the i-th attribute.
  • the attribute instance identifier (attribute_instance_id[ i ]) indicates an instance ID for the i-th attribute.
  • 25 shows a set of geometric parameters according to embodiments.
  • Fig. 25 is a set of geometry parameters included in the bitstream of Fig. 23;
  • the method/apparatus according to the embodiments may provide efficient signaling by including information related to prediction tree generation according to the embodiments in a geometry parameter set.
  • GPS Geometry Parameter Set ID (gps_geom_parameter_set_id): Provides an identifier for the GPS for reference in other syntax elements.
  • the value of gps_seq_parameter_set_id may be in the range of 0 to 15.
  • GPS sequence parameter set ID (gps_seq_parameter_set_id): Indicates a sps_seq_parameter_set_id value for an active SPS.
  • the value of gps_seq_parameter_set_id may be in the range of 0 to 15.
  • 26 shows a tile parameter set according to embodiments.
  • Fig. 26 is a tile parameter set included in the bitstream of Fig. 23;
  • the method/apparatus according to the embodiments may provide efficient signaling by including information related to prediction tree generation according to the embodiments in a tile parameter set.
  • GPS Geometry Parameter Set ID (gps_geom_parameter_set_id): Provides an identifier for the GPS for reference in other syntax elements.
  • the value of gps_seq_parameter_set_id may be in the range of 0 to 15.
  • GPS sequence parameter set ID (gps_seq_parameter_set_id): Indicates a sps_seq_parameter_set_id value for an active SPS.
  • the value of gps_seq_parameter_set_id may be in the range of 0 to 15.
  • num_tiles The number of tiles (num_tiles) indicates the number of tiles signaled for the bitstream. If it does not exist, num_tiles is inferred to be 0.
  • tile bounding box offset X (tile_bounding_box_offset_x[ i ]) indicates the x offset of the i-th tile in Cartesian coordinates. If it does not exist, the value of tile_bounding_box_offset_x[ 0 ] may be inferred to be sps_bounding_box_offset_x.
  • tile bounding box offsetY (tile_bounding_box_offset_y[ i ]) represents the y offset of the ith tile in Cartesian coordinates. If it does not exist, the value of tile_bounding_box_offset_y[ 0 ] may be inferred as sps_bounding_box_offset_y.
  • tile bounding box offsetZ (tile_bounding_box_offset_z[ i ]) represents the z offset of the i th tile in Cartesian coordinates. If it does not exist, the value of tile_bounding_box_offset_z[ 0 ] may be inferred as sps_bounding_box_offset_z.
  • FIG. 27 illustrates a geometry slice header according to embodiments.
  • Fig. 27 is a geometry slice header included in the bitstream of Fig. 23;
  • the method/apparatus according to the embodiments may provide efficient signaling by including information related to prediction tree generation according to the embodiments in a geometry slice header.
  • Prediction origin Indicates an origin position value applied in the corresponding slice.
  • the GSH geometry parameter set ID (gsh_geometry_parameter_set_id) indicates a gps_geom_parameter_set_id value of the active GPS.
  • the GSH tile identifier indicates the value of the tile ID referenced by the GSH.
  • the value of gsh_tile_id can range from 0 to XX.
  • the GSH slice ID (gsh_slice_id) may identify a slice header to be referenced by other syntax elements.
  • the value of gsh_slice_id can range from 0 to XX.
  • Transmitting device 10000 in Fig. 1 point cloud video encoder 10002, transmitter 10003, Acquisition-encoding-transmitting (20000-20001-20002) in Fig. 2, Encoder in Fig. 4, Transmitting device in Fig. 12, Fig.
  • the device for transmitting point cloud data such as the device of 14 and the encoder of FIG. 21 may encode and transmit the point cloud data by the following steps.
  • a method of transmitting point cloud data may include encoding the point cloud data.
  • the encoding step according to the embodiments may include: FIG. 1 transmitting apparatus 10000, point cloud video acquisition 10001, point cloud video encoder 10002, FIG. 2 acquisition-encoding 20000-20001, FIG. 4 encoder, FIG. 12 transmission
  • the device, the XR device 1430 of Fig. 14, the origin position selection according to Figs. 15-20, point alignment, prediction tree generation, Fig. 21 encoder, Fig. 23-27 bitstream and parameter generation, and the like may be included.
  • the method for transmitting point cloud data may further include transmitting a bitstream including the point cloud data.
  • Transmission operation according to the embodiments is shown in Fig. 1 transmission apparatus 10000, transmitter 10003, Fig. 2 transmission 20002, Figs. 4, 12, 14 transmission of geometry bitstreams and attribute bitstreams, and encoding according to Figs. 15-20. It may include an operation such as transmission of the bitstream (FIGS. 23-27) including the point cloud data.
  • 29 shows a method of receiving point cloud data according to embodiments.
  • Receiver 10004, receiver 10005, point cloud video decoder 10006, transmit-decode-render (20002-20003-20004) in Fig. 2, decoder in Figs. 10-11, receiver in Fig. 13 , the device of FIG. 14 , the decoder of FIG. 22 , and the like point cloud data receiving apparatus may receive and decode the point cloud data by the following steps.
  • the process of the receiver side may follow the reverse process of the process of the sender.
  • a method for receiving point cloud data may include receiving a bitstream including point cloud data.
  • Receiving according to the embodiments may include: Fig. 1 receiving device 10004, receiver 10005, Fig. 2 receiving according to transmission 20002, Fig. 10-11 Geometry bitstream and attribute bitstream receiving, Fig. 13 receiving device; It may include operations such as receiving the point cloud data encoded by the XR device 1430 of FIG. 14, FIGS. 15-20, and the like, the decoder of FIG. 22, and receiving the bitstream of FIGS. 23-27.
  • the method for receiving point cloud data may further include decoding the point cloud data.
  • Decoding operations according to the embodiments are shown in Fig. 1 point cloud video decoder 10006, renderer 10007, Fig. 2 decoding-renderer-feedback 20003-20005, Fig. 10-11 decoding, Fig. 13 receiving/decoding, Fig. 15 It may include operations such as restoration of point cloud data encoded by -20 and the like, and restoration of geometry data and attribute data included in the decoder of FIG. 22 and the parameter-based bitstream of FIGS. 23-37.
  • the method/apparatus according to the embodiments may re-order geometry data (positions of points) for geometry prediction tree coding.
  • the points since the laser sensor rotates at a constant angle in the process of capturing the point through the laser sensor, the points have a laser angle property (see FIG. 15 ).
  • the method for using this laser angle can be applied to determine a point for realigning the points.
  • the points may have a laser angle, and the laser angle is used to determine the origin.
  • the point may be selected and determined by the method/apparatus according to the embodiments according to the following settings.
  • the center laser angle may be 90 degrees. It may be a point located at the far left.
  • 17-18 show selected origins 18001, 08004 and 18007 for each slice.
  • a re-ordering method based on laser angle A re-ordering method based on laser angle:
  • the laser angle is used to realign the points instead of the calculated azimuth.
  • the points are aligned according to the laser angle value (laser angle range).
  • the points may be arranged based on color, which is a property of the points. For example, if the points are rearranged by the laser angle, the result may be obtained that the points are arranged in an example order such as yellow points, green points, orange points, green points.
  • encoding the point cloud data; and transmitting a bitstream including the point cloud data may include.
  • the encoding of the point cloud data may include encoding geometry data of the point cloud data, and the geometry data may be encoded based on the laser angle for the point cloud data.
  • the method/device in relation to the origin position and point alignment, provides that the geometric data of the point cloud data has a laser angle, the laser angle is 90 degrees, and the point that is the leftmost coordinate It can be selected as the origin of the geometric data.
  • geometric data may be aligned based on laser angle.
  • a method in relation to generation of a prediction tree generates a prediction tree having a point having the latest laser angle as a parent based on the laser angle, and a second laser group including a plurality of points.
  • a root node may be set as a parent node of a root node of a first laser group including a plurality of points, and the laser angle value of the second laser group may be smaller than that of the first laser group.
  • the latest meaning is interpreted to refer to a point in the first position in the aligned state, or a point having a small laser angle value.
  • the encoding of the point cloud data includes encoding the geometry data of the point cloud data
  • the encoding of the geometry data includes transforming the coordinate system of the geometry data to a laser Set the origin based on the angle, sort the geometric data based on the origin, create a prediction tree based on the sorted geometric data, generate the predicted value of the point cloud data based on the prediction tree, and the residual value from the prediction value. , to generate a geometry bitstream.
  • the PCC encoding method, the PCC decoding method, and the signaling method of the embodiments may provide the following effects.
  • Angle mode can be applied to the scenario of capturing and saving frame by frame through LiDAR equipment, but when multiple frames are captured with LiDAR equipment to create 3D map data and integrated into one content Because the data with different central positions of the lidar equipment are mixed, the angular characteristics that appear in the data captured by the lidar equipment, that is, the angle When changing to , the rule between points may be hidden, and applying an angle mode to it may not be more efficient than compression based on the Cartesian coordinate system.
  • a method for increasing the compression efficiency from the regularity of the points in the content may be needed even for 3D map data.
  • the embodiments describe an origin selection method, an alignment method, and a method of quickly constructing a prediction tree for the prediction tree-based efficient geometry compression of 3D map data captured through lidar equipment and integrated into one content. supported.
  • embodiments provide a point cloud content stream by increasing the geometry compression efficiency of the encoder (encoder)/decoder (decoder) of Geometry-based Point Cloud Compression (G-PCC) for 3D point cloud data compression can do.
  • the PCC encoder and/or PCC decoder may provide an efficient prediction tree generation method, and may provide an effect of increasing geometry compression coding/decoding efficiency by considering the degree of influence between prediction points.
  • the transmission method/device according to the embodiments may transmit data by efficiently compressing the point cloud data, and by delivering signaling information for this, the receiving method/device according to the embodiments also efficiently transmits the point cloud data It can be decoded/restored.
  • Various components of the apparatus of the embodiments may be implemented by hardware, software, firmware, or a combination thereof.
  • Various components of the embodiments may be implemented with one chip, for example, one hardware circuit.
  • the components according to the embodiments may be implemented with separate chips.
  • at least one or more of the components of the device according to the embodiments may be configured with one or more processors capable of executing one or more programs, and the one or more programs may execute Any one or more of the operations/methods according to the examples may be performed or may include instructions for performing the operations/methods.
  • Executable instructions for performing the method/acts of the apparatus according to the embodiments may be stored in non-transitory CRM or other computer program products configured for execution by one or more processors, or one or more may be stored in temporary CRM or other computer program products configured for execution by processors.
  • the memory according to the embodiments may be used as a concept including not only a volatile memory (eg, RAM, etc.) but also a non-volatile memory, a flash memory, a PROM, and the like. Also, it may be implemented in the form of a carrier wave, such as transmission through the Internet.
  • the processor-readable recording medium is distributed in a computer system connected to a network, so that the processor-readable code can be stored and executed in a distributed manner.
  • first, second, etc. may be used to describe various components of the embodiments. However, the interpretation of various components according to the embodiments should not be limited by the above terms. These terms are only used to distinguish one component from another. it is only For example, the first user input signal may be referred to as a second user input signal. Similarly, the second user input signal may be referred to as a first user input signal. Use of these terms should be interpreted as not departing from the scope of the various embodiments. Although both the first user input signal and the second user input signal are user input signals, they do not mean the same user input signals unless the context clearly indicates otherwise.
  • the operations according to the embodiments described in this document may be performed by a transceiver including a memory and/or a processor according to the embodiments.
  • the memory may store programs for processing/controlling operations according to the embodiments, and the processor may control various operations described in this document.
  • the processor may be referred to as a controller or the like. Operations in embodiments may be performed by firmware, software, and/or a combination thereof, and the firmware, software, and/or a combination thereof may be stored in a processor or stored in a memory.
  • the transceiver device may include a transceiver for transmitting and receiving media data, a memory for storing instructions (program code, algorithm, flowchart and/or data) for a process according to embodiments, and a processor for controlling operations of the transmitting/receiving device.
  • a processor may be referred to as a controller or the like, and may correspond to, for example, hardware, software, and/or a combination thereof. Operations according to the above-described embodiments may be performed by a processor.
  • the processor may be implemented as an encoder/decoder or the like for the operation of the above-described embodiments.
  • the embodiments may be wholly or partially applied to a point cloud data transmission/reception device and system.
  • Embodiments may include variations/modifications without departing from the scope of the claims and the like.

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